Brushes have been used for many years to polish, clean and abrade a wide variety of substrates. These brush products typically have a plurality of bristles that contact the substrate. Abrasive particles can be added to bristles to increase their abrasiveness. There are many manufacturing steps necessary to manufacture a conventional abrasive brush. A mixture of a thermoplastic binder and optional abrasive particles may be combined and then extruded to form a bristle. The bristle is then cut to the desired length. A plurality of these bristles are then mechanically combined to form a brush segment. Next, a plurality of these brush segments may be installed on a hub or plate to form a brush.
One example of such a brush is disclosed in U.S. Pat. No. 5,045,091, "Method of Making Rotary Brush With Removable Brush Elements," (Abrahamson et al.). In Abrahamson et al., a plurality of abrasive bristles are mechanically clamped together and a root system is installed to form a brush segment. A plurality of these brush segments are installed on a rotary hub. Another arrangement for mechanically mounting bristles on a hub to form a brush segment is disclosed in U.S. Pat. No. 5,233,719, "Apparatus and Brush Segment Arrangement for Finishing Wheel Brushes," (Young et al.). Young et al. teach a brush segment comprising a substrate with a carpet of bristles mounted on one side of the substrate, by means of a polymeric resin for example, and a root system extending from the opposite side of the substrate for engagement with a rotary hub. U.S. Pat. No. 5,400,458 (Rambosek) teaches a brush segment having a plurality of bristles embedded in a polymeric base portion. A root means for attaching the segment to a hub can be integrally molded with the base.
U.S. Pat. No. 3,618,154, "Brush," (Muhler et al.), discloses brushes, and more particularly an integrally molded, one-piece brush, especially a toothbrush, in which the plastic material from which the brush is molded incorporates up to about 30% by weight of an abrasive material, especially a dental abrasive material. Muhler states that, depending upon the individual use to which the brush may be put, the abrasive component thereof may be omitted.
U.S. Pat. No. 3,233,272, "Rotary Brush," (Pambello), discloses brushes, particularly rotary brushes of the annularly or spirally arranged brush strip type which are primarily adapted for heavy duty such as brushing paved streets, sidewalks, concrete flooring and the like. In one embodiment, the rotary brush of Pambello comprises a rotatable structure, a brushing element formed of a unitary strip of yieldable plastic material annularly arranged on the structure, the strip having a lengthwise extending base and having vane means extending outwardly from the base and formed with a tip at the outer end thereof The brush strip of Pambello may be formed of plastic materials by molding or extruding and cutting operations.
U.S. Pat. No. 5,233,794, "Rotary Tool Made of Inorganic Fiber-Reinforced Plastic," (Kikutani et al.), discloses a rotary tool 5 having a rotating tip formed integrally with a shaft 3. The rotary tool is formed of a thermosetting resin containing inorganic long fibers with a high degree of hardness as an abrasive means in an amount from 50% to 81% by volume. The long inorganic fibers can have a diameter in the range of 3 .mu.m to 30 .mu.m. In one of the embodiments of Kikutani et al., the rotating tip is formed as a column or cylinder with elements 6 which correspond to the bristle of a brush extending from the tip, as is reproduced in FIG. 10.
U.S. Pat. Nos. 5,152,917 and 5,304,223 (Pieper et al.) teach coated abrasive articles comprising precisely shaped abrasive composites bonded to a backing. The abrasive composites comprise binder and abrasive particles. The precisely shaped composites can be in the form of, for example, pyramids, sawtooth grooves, or linear grooves. The maximum distance between corresponding points on adjacent composite shapes can be less than one millimeter. The coated abrasive of Pieper et al. can be made, for example, according to the following general procedure. First, a slurry containing abrasive grains and binder is introduced to a production tool. Second, a backing is introduced to the outer surface of the production tool such that the slurry wets the front side of the backing. Third, the binder is at least partially cured. Fourth, the production tool is removed from the backing.
U.S. Pat. No. 5,316,812 (Stout et al.) teaches a thermoplastic backing for use in abrasive articles. A resinous binder adheres abrasive particles to the thermoplastic backing.
U.S. Pat. Nos. 5,174,795 and 5,232,470 (Wiand) teach a planar abrasive article comprising a sheet portion with a plurality of protrusions extending therefrom. Abrasive particles are homogeneously dispersed throughout the moldable material comprising the article. Wiand teaches one embodiment having short protrusions extending 1.6 mm (0.063 in) from the backing and having a 3.2 mm (0.125 in) diameter, and another embodiment having short protrusions extending 1.3-1.5 mm (0.05-0.06 in) from the backing and having a 1.3 mm (0.05 in) diameter.
G.B. Patent Application No. 2.043,501, (Dawkins) discloses an abrasive article for polishing ophthalmic workpieces. The abrasive article is made by injection molding a mixture of abrasive grains and a thermoplastic binder to form an abrasive article comprising a flexible backing having a plurality of upstanding projections, the ends of which act as operative abrading surfaces.
U.S. Pat. No. 5,427,595 (Pihl) discloses an extruded abrasive filament including a first elongate filament component having a continuous surface throughout its length and including a first hardened organic polymeric and a second elongate filament component coterminous with the first elongate filament component, including a second hardened organic polymeric material in melt fusion adherent contact with the first elongate filament component along the continuous surface. The second hardened organic polymeric material can be the same or different than the first hardened organic polymeric material. At least one of the first and second hardened organic polymeric materials includes a thermoplastic elastomer having abrasive particles adhered therein. Also disclosed is an abrasive article comprised of at least one abrasive filament mounted to a substrate such as a hub adapted to be rotated at a high rate of revolution.
U.S. Pat. No. 5,460,883 (Barber) discloses a composite abrasive filament which includes at least one preformed core at least partially coated with a thermoplastic elastomer having abrasive particles dispersed and adhered therein, the thermoplastic elastomer and abrasive particles together comprising a hardened composition. The composite abrasive filament has a hardened composition over at least a portion, preferably over the entire surface of at least one preformed core. The preformed core is formed in a step separate from and prior to one or more coating steps, one of which coats the preformed core with abrasive-filled thermoplastic elastomer.
It is seen that there is a need to provide a molded brush that is easily and inexpensively manufactured, and which provides suitable durability and performance characteristics.